Audacity Selection

From Audacity Manual

Special characteristics of audio selection

In a word processor, most operations are performed by selecting a range of text (usually with the mouse), then choosing some option from a toolbar or menu, for example to cut the text, or make it bold. Audacity works much the same way; most operations are performed by selecting audio with the mouse and then applying some operation.

Audacity selections can be more complicated than word processor selections, though. In Audacity, the selection involves a set of selected tracks, and then a range of time within those selected tracks. This is because sometimes you might want to select multiple tracks so that any changes you make apply to all of them, but other times you might want to affect the tracks individually. In either case, you may or may not want the edits to apply to the whole time range of the tracks.

Normally, you select both the tracks and the time range simultaneously, by clicking and dragging. For example, to create the following selection, make sure you're using the Selection tool and click the cursor at 5.0 seconds in the first track, and drag rightwards to 7.0 seconds on the timeline so that the gray selection area extends down into the second track:

Note that the selection area does not extend down to the third track because that track is not selected. Therefore, any operation you perform will now only affect the selected area of the first two tracks.

It's possible to change the selected time range and which tracks are selected independently. To change the selected time range, you have several options:

• Move the mouse cursor to one of the edges of the selection until it changes to a different pointer. Click and drag to change that edge of the selection.
• Shift-click near one of the edges of the selection to extend or contract the selection to the time point you clicked on.
• Use SHIFT + LEFT, SHIFT + RIGHT, CTRL + SHIFT + LEFT, and CTRL + SHIFT + RIGHT to move the two edges of the selection in either direction.

To change which tracks are selected without affecting the time range, you also have multiple options:

• Shift-click on the Track Panel to the left of the waveform to toggle its selection.
• Press SHIFT + UP, SHIFT +DOWN, CTRL + SHIFT + UP, and CTRL + SHIFT + DOWN to extend or contract the selection up or down tracks.
• Press UP or DOWN to change the focused track, then press the Enter key to toggle its selection.

Note that it is possible to have a time range selected but no tracks selected. In that case, you will only see the evidence of the selected time range in the timeline.

Audio editing is different from text editing in another way, too. With audio, it usually isn't obvious from the waveform what you want to select, so you really want to listen just to the left and right edges of a selection to make sure you are editing the correct part. But if you are new to audio editing, don't worry. For now, you can just click and drag to create a selection on a single track, and hit Space to listen to all of it. Come back here for more help when you start to work on more advanced projects and are having trouble selecting what you want.

Selecting using the mouse

The easiest way to select a range of audio is to click and drag. If it's not already chosen, choose the Selection tool from Tools Toolbar, below:

Now click the left mouse button anywhere inside of an audio track, and click and drag to the other edge of your selection, and release. Some tips:

• You can drag from left to right or from right to left, it doesn't matter.
• You can start your selection in one track, and end it in another track, and both tracks (plus the tracks in-between) will all end up selected.
• If you move the mouse past the left or right edge of the window while dragging, Audacity will scroll the window in that direction as long as the mouse button is down.

To extend or contract an existing selection, hold down the Shift key while clicking the mouse. The nearest edge of the selection will jump to the current mouse cursor location. This is really useful if you know exactly what you want to select but it doesn't easily fit on the screen at once:

• Click at one edge of the selection.
• Scroll until the other edge is in view.
• Shift-click to set the other edge of the selection.

You can also extend or contract a selection by positioning the mouse near the edge of a selection, then clicking and dragging. The selected portion of a track with the cursor is changed to a pointing hand, see below:

The cursor changes to a pointing hand when you are near the edge of a selection, so you know when you can click and drag to extend or contract the selection.

Selection Toolbar

One handy way to keep track of what you've selected and to make precise modifications is to use the Selection Toolbar (shown above). For our purposes here, let's concentrate on the main purpose of the bar, the Selection Start and End/Length boxes. By changing the radio button from "End" to "Length", you can display and control the length of the selection instead of the endpoint. Which one is useful for you depends on the circumstances: if you need a clip from a song that's exactly 30 seconds long, you may want to set the length to 30, and then modify the start until you have just what you want. Other times you may know the exact end time but need to figure out where to start, independent of the resulting length.

You can edit the time displayed in Selection Toolbar using the mouse and/or keyboard. To change a particular digit, you can just click on it and type a new value:

You can also edit the boxes in Selection Toolbar entirely using the keyboard:

Key	Action
CTRL + F6	Move the focus to/from Selection Toolbar
TAB	Move between controls in Selection Toolbar
LEFT / RIGHT	Move cursor in a Selection Toolbar control
UP / DOWN	Increase or decrease the highlighted digit
BACKSPACE	Reset the last number entered to zero

In the figure above, the selection is displayed in units of hours, minutes, and seconds. As shown, it doesn't display any more accuracy than that, so it's hard to tell if you have half of a second selected, which can be very important sometimes. That's no problem, because Audacity gives you many ways to display the time in the selection toolbar. To get these choices, click on the right triangle to the right of each box, or alternatively, right-click anywhere in the box to open the context menu:

The different time formats are listed in the table below. It's okay if most of them don't mean anything to you. Most of them are intended for people using Audacity for very specific purposes, especially editing soundtracks for video, and those people will know which one they want.

Selection Name	Example	Notes
seconds	005,408 seconds
hh:mm:ss	01 h 30 m 08 s	Hours, minutes, seconds
dd:hh:mm:ss	00 days 01 h 30 m 08 s	Days, hours, minutes, seconds
hh:mm:ss + milliseconds	01 h 30 m 08.500 s
hh:mm:ss + samples	01 h 30 m 08 s + 22500 samples	Based on your chosen sample rate
samples	238,514,850 samples
hh:mm:ss + film frames (24 fps)	01 h 30 m 08 s + 12 frames
film frames (24 fps)	129,804 frames
hh:mm:ss + NTSC drop frames	01 h 30 m 08 s + 14 frames	American video format
hh:mm:ss + NTSC non-drop frames	01 h 30 m 03 s + 02 frames
NTSC frames	162,092 frames
hh:mm:ss + PAL frames (25 fps)	01 h 30 m 08 s + 12 frames	European video format
PAL frames (25 fps)	135,212 frames
hh:mm:ss + CDDA frames (75 fps)	01 h 30 m 08 s + 37 frames
CDDA frames (75 fps)	405,637 frames	Audio CD frames

Selecting using the keyboard

You can modify the selection entirely using the keyboard. The currently focused track is indicated with a glowing border, as you can see from the track called "Guest" in this image:

To change the focused track, just press the up and down arrow keys. In this image, we pressed down arrow to change focus to the "Bkgnd" track:

Once a track is focused, press ENTER or RETURN to change it from being selected to not selected, or from not selected to selected.

To modify the time range, press the left and right arrow keys in combination with SHIFT + CTRL. If you don't already have a selection, just a cursor, then pressing the left or right arrow keys will move the cursor. If you do have a selection, pressing the left arrow will take you to the beginning of the selection, and the right arrow will take you to the end.

If you hold down Shift while pressing the right arrow, you can extend the selection to the right. Similarly, SHIFT + LEFT extends the selection to the left.

CTRL + SHIFT contracts the selection. CTRL + SHIFT + LEFT contracts the right edge to the left, and CTRL + SHIFT + RIGHT contracts the left edge to the right.

Selecting while audio is playing

Sometimes the easiest way to select an exact portion of audio is to mark the selection boundaries while you're playing audio. To do this, press the '[' key to mark the left edge of the audio, and the ']' key to mark the right edge.

After you've done that, you'll definitely want to listen to the resulting selection to make sure it was right. Press Space to hear just the selection. There are additional keyboard shortcuts that let you listen to just the beginning or end of a selection - see Special Playback Keyboard Commands for details.

Snap-to Guides

Audacity makes it really easy to make a selection that starts or end at a natural boundary, like a label or clip boundary.

The current version of Audacity has support for a new type of snapping, in addition to the Snap To checkbox in the Selection Toolbar. For the new snapping, when you take the following actions:

• Creating a selection with the mouse
• Modifying the selection boundaries
• Sliding / time-shifting a clip

the selection boundaries or the boundaries of the clip you're time-shifting will snap to the following locations:

• Time zero (0 on the Timeline)
• The start or end of any track or clip
• The start or end of any label

Whenever snapping is taking place, a yellow vertical line appears to indicate snapping is taking place. To err on the side of caution, if there is more than one logical place within a couple of pixels at which to snap, Audacity will not snap anywhere. In that case, zoom in.

In the image below, we're dragging a clip in the "Guest" track leftwards with the mouse. When the clip reaches the right-hand boundary of the clip above it, a yellow vertical guide line appears showing the position of the snap boundary through all the tracks. Now that the guide line has appeared, we can release the mouse and the dragged clip will be perfectly aligned with the one above:

A Snap Guide appears (the vertical yellow line) when the selection has snapped to the start or end of an audio clip from any of the tracks.

If there are two boundaries very close to one another and it's not obvious which one is better, Audacity will not snap to either. If you want to snap to one of them, zoom in so that you can clearly position the mouse closer to one than the other.

Track Selection using the mouse

There are two very useful things you can do by clicking in the label area to the left of a track - make sure that you click in a neutral area, not inside one of the buttons or sliders. See Audio Tracks for more about the Track Panel.

Clicking on a track's label area will select the entire track. That's a very easy way to apply an effect to an entire track. If you want to select all tracks, you can alternatively choose Select All from the Edit menu.

There's another handy way to select an entire track or clip: just double-click inside of it.

If you hold down Shift while clicking on a track's label, you can toggle the selection of that track. For example, if you want to select the first and third tracks only, you could choose Select All and then shift-click on the middle track to deselect it while leaving the others selected.

Note that it is possible to have a time range selected but no tracks selected. In that case, you will only see the evidence of the selected time range in the timeline.

Menu commands for selecting

The Edit menu has several commands that are useful for selecting:

Command	Action
Select... All	Select all audio in all tracks
Select... None	Deselect everything and move the cursor to 0.0
Left at Playback Position	Sets the left selection boundary based on audio playback
Right at Playback Position	Sets the right selection boundary based on audio playback
Start to Cursor	Select from the start of the track or clip to the cursor position.
Cursor to End	Selection from the cursor position to the end of the track or clip.
Region Save	Remembers the current selection time range
Region Restore	Restores the time range from Selection Save

Label Tracks

A very useful way to recall particular selections is to label them in a label track. For more information, see Label Tracks.